Product applicators are designed to deliver a quantity of product to a target surface. In consumer goods there are, broadly, two types of applicators. There are applicators that are separable from a product container/reservoir and there are applicators that are integral with a product reservoir. A “separable applicator” is one that is disconnected from a product reservoir at the time of applying product to a target surface. In use, a separable applicator is loaded with product from a product reservoir for transfer to a target surface. In contrast, applicators that are integral with a product reservoir (herein, “integral applicators”) cannot be separated from the product reservoir. An integral applicator may be thought of as having a reservoir portion and an applicator portion. This type of device dispenses product by causing the product to flow from the reservoir, through the interior of the applicator portion, out an exit structure onto an exterior surface of the applicator portion, from where the product may be transferred to a target surface.
Either applicator type is known to be coupled with a heating element to raise the temperature of a product prior to and/or during dispensing and application. However, these two types of applicators have different strengths and weaknesses, different design and use issues, and different problems associated with incorporating heating means into their respective interiors. Therefore, a heated integral applicator has different issues than a heated separable applicator, as now briefly discussed.
Heating means may be added to a separable applicator in one of two ways. In the first case, the heating means is associated with the reservoir. The disadvantages of this include subjecting all of the product in the reservoir, or at least more than will be used, to repeated temperature cycles, possibly damaging the product. Also, heat is lost in the time it takes to transfer the product from the reservoir to the target surface. Also, it will generally take longer to raise the temperature of the product to application temperature because more is being heated. In the second case, the heating means is associated with the applicator. The disadvantages of this include the need to house the electronic circuitry and heating means solely within the applicator. This is a serious problem in cosmetics and personal care applicators which tend to be sleek and designed for easy storage in a small purse or pocket. In the personal care field, often the drive is to make applicators smaller and more convenient, not bulkier. Therefore, when the addition of heating components to an applicator requires making the applicator larger, this is a clear disadvantage.
In contrast, to incorporate heating means, integral applicators do not have to be enlarged at all or to the same degree as separable applicators. Some of the disadvantages of heated separable applicators are overcome in a dispensing container with integral applicator because the heat can be generated in the applicator portion, while the electronics can be housed within the container/reservoir portion. Thus, only the product being dispensed is heated and there is no need to enlarge the applicator. The container portion provides sufficient space for a layout of electric circuits and comparatively little of the circuitry is housed within the applicator portion. Thus, integral applicators with heating means may be no larger than integral applicators having no heating means. Integral applicators that heat a product prior to or at the time of dispensing are known. Specifically, there are such devices in the fields of cosmetics and personal care. The following will make clear the shortcomings of known devices of this type.
U.S. Pat. No. 4,291,685 discloses a handheld cosmetic applicator “for applying heat and medicament, unguents, cosmetics and the like to the face or other parts of the body.” The applicator comprises a dispensing means that consists of a plunger that is slidable within a hollow interior of a tubular handle. The plunger is moved by the action of a user's thumb against an actuator that slides in a slot in the handle. The disadvantage of the plunger is that it is difficult to control the amount of product dispensed and the rate at which it is dispensed. Therefore, product heating may be uneven from dose to dose. Also, the plunger takes up space inside the reservoir. Furthermore, the '685 device is unsuitable for products that flow, either at ambient temperatures or after being heated. Liquids would leak from the '685 device, out the exit orifices because no means of containing the product is disclosed. Also, the sliding plunger mechanism is not an efficient means of dosing a flowable liquid because the amount dosed would be difficult to control. Clearly, the '685 device should not be used with liquid products that readily flow at ambient temperatures or that flow after being heated.
In the '685 device, the heating means includes an electrically resistive element, an electrical cord connected to a rheostat and a plug for connecting to an electrical power source. Thus, this device relies on ordinary household current and a rheostat to adjust the electrical current that is delivered to the resistive element. Disadvantages of the prior art electrical system include the following: electrical cords tend to deteriorate and be unwieldy; the plug-in power cord does not offer the mobility and safety of batteries; the voltage used is much higher than that of batteries; the internal circuitry consists of extended runs of wiring which is difficult and costly to assemble into the housing, compared to a prefab, printed circuit board; the device has user activated on-off switches, which means that the device may be left on, unintentionally.
Furthermore, the '685 prior art device is intended to contact the skin for an extended time. Hence, a need for the consumer to be able to control temperature via a variable rheostat. The rheostat control is in the form of “a sleeve mounted for rotatable movement around the outer periphery of said handle for controlling said rheostat.” The need to include a rheostat is a potential disadvantage of the prior device. The rheostat design is complex and adds bulky electronics to the device and their associated costs. The rheostat creates an unsuitable appearance for a cosmetic applicator. The rheostat may be moved accidentally during use. The rheostat adds size, bulk and cost to the device.
Furthermore, this device offers a vibrating massage effect when contacting the body. To achieve the massage effect, the vibrating application surface, where dispensed product accumulates before application, is flat and extended. A disadvantage of the extended application surface is that the product application is not precise, because product is spread out over the extended surface. Such a surface is unsuitable for applying product to any relatively small area requiring a confined dose of product, for example, to the eye area. Furthermore, the relatively large application surface and the massaging vibration work a product crudely into the skin. In contrast, various personal care products for making up or care of the skin should not be applied in a crude manner. They should be applied with precision and care, targeted to each specific area. Clearly, the '685 prior art device is not suitable for use as a targeted personal care applicator and other massage devices would suffer from similar drawbacks.
Furthermore, the flat application surface is smooth or textureless and relatively hard. A softer surface would render the '685 device inoperative, or at least less effective, by damping the massage vibration. A textured vibrating surface may irritate the skin. For these reasons, this prior art device should not be provided with a foam or flocked application surface. Not having a flocked or foamed tip is a drawback of the prior art, because a flocked or foamed tip provides a soft and luxurious product application.
All of this is in contrast to the present invention, wherein: there is no plunger to take up space; there are no or few electrical cords; the device is much less likely to be left on unintentionally and even if it is, it would only continue at a relatively low voltage until the batteries drained, thus it is safer; there is no need for a rheostat; the applicator surface is suitable for precise dosing to a targeted area; the applicator surface my be textured or flocked or otherwise provided with any sort of feel; the applicator is suitable for flowable products, without leaking. To the extent that prior art devices share one or more characteristics of the '685 device, they too are inferior to the present invention.
There are a large number of devices for applying a wax or thermoplastic material to the skin. Examples include those disclosed in U.S. Pat. Nos. 5,395,175; 5,556,468; and 5,831,245. Generally, in devices of this type the product to be applied to the skin is substantially solid at room temperature. To achieve flowability, the product must be heated while it is still in the reservoir. Heating the entire reservoir has the disadvantage of subjecting the entire contents of the container to repeated temperature cycles. Therefore, this kind of applicator is clearly only suitable for products that are not substantially affected by temperature cycling, i.e. some waxes. In contrast, many cosmetic and dermatologic products are unstable when subjected to temperature cycling. For products that will be changed structurally or chemically by the application of too much heat or from being too often heated, these prior art devices are wholly unsuitable. Therefore, prior art devices that heat even a portion of the reservoir, or that heat more product than will be used, are unsuitable for many cosmetic applications.
Another disadvantage of devices that heat the reservoir, or that heat more product than will be used, is the power consumed. Far more power must be consumed by these devices because they aim to raise the temperature of a greater mass of product than the present invention. This is costly and inconvenient if batteries need to be replaced often. In acknowledging this problem, many of these prior art devices provide thermal insulation to keep the heat inside the reservoir. Of course, this adds complexity and cost. In some prior art devices, the power source is separate from the applicator and the applicator needs to be rejoined to the power source in order to heat the product. Such devices do not offer the convenience and portability of a self-contained cosmetic applicator.
All of this is in contrast to the present invention, wherein: the product remaining in the reservoir is not substantially heated and remains in good condition for future use; relatively little power is consumed; no thermal insulation is required; and the power source is integral with the applicator so that continuous heating and convenient portability are achieved.
U.S. Pat. No. 4,465,073 describes an appliance for wax depilation especially of the face. A nozzle having an external opening located at the tip of the outer casing of the appliance is intended to be held close to the user's skin. A heater adjacent to the duct melts the wax which is engaged within the duct. A plunger (“carriage”) for receiving the block of wax within the appliance is intended to be pushed by hand towards the duct by means of an external thumb control button. This device does have the advantage that the wax in the reservoir is not directly heated because the heating means has been associated with the applicator portion of the device. However, like U.S. Pat. No. 4,291,685, above, this device relies on the action of a user's thumb against an actuator (or “carriage”) to advance the product. The disadvantage of this is that it is difficult to control the amount of product dispensed and the rate at which it is dispensed. Therefore, product heating may be uneven from dose to dose. Also, the carriage mechanism is again unsuitable for readily flowable liquid products. Also, the plunger takes up space inside the reservoir. The heating means includes a thermistor, an electrical cord and plug for connecting to an electrical power source. Thus, this device relies on ordinary household current. Disadvantages of the prior art electrical system include the following: electrical cords tend to deteriorate and be unwieldy; the plug-in power cord does not offer the mobility and safety of batteries; the voltage used is much higher than that of batteries; the internal circuitry consists of extended runs of wiring which is relatively difficult and costly to assemble into the housing; it is easy to leave the device on when not in use.
All of this is in contrast to the present invention, wherein: there is no plunger to take up space; there are no or few electrical cords; the internal circuitry consists of a prefab, flexible, printed circuit which is relatively easy and inexpensive to assemble into the housing; the device is much less likely to be left on unintentionally and even if it is, it would only continue at a relatively low voltage until the batteries drained, thus it is safer; relatively little power is consumed; and the applicator is suitable for flowable products, without leaking.